DE 197 18 618 C2 describes a composite structure in which microelectronic components, such as transistors, diodes, resistors, capacitors, inductive resistors, etc., or circuits made thereof, such as amplifiers, sensors, emission cathodes for electrons, etc., placed on a growth substrate of monocrystalline silicon are provided with a diamond thermoconductive layer. The printed publication also discloses a corresponding plasma CVD for applying the diamond layer. The thermoconductive layer is made of diamond, among other things, because this material also possesses good thermoconductivity despite electric insulation. Such a type of thermoconductive layer made, in particular, of polycrystalline diamond is, therefore, excellently suited for thermal management of microelectronic components.
However, depositing the diamond layer on the components must occur at, for epitaxial growth, low temperatures in order not to impair or even destroy the components.
Furthermore, despite the thermal expansion differing from that of the coated materials, adhesion of the diamond layer to the coated surface has to be good. Due to these conditions, the epitaxial growth of aforementioned diamond thermoconductive layer must be conducted with great care.
With, in particular, growth substrates and/or components provided with binary, ternary, quaternary or even higher grade compound semiconductors, there is the problem that these materials react very strongly with the hydrogenous plasma during application of the diamond, thereby destroying and/or even completely removing these materials.
EP 0681 314 A2 describes the production of a composite structure in which a crystalline-arranged, i.e. heteroepitactic in relation to the substrate, diamond layer is deposited on a suited monocrystalline growth substrate, e.g. of Si or GaAs, by means of an intermediate layer with a continues lattice structure. The goal is a structurally high grade diamond layer that is suited for production of electronic components on a diamond base. The purpose of the substrate is to permit oriented diamond growth and therefore the substrate contains no electronic components. A lattice constant similar as closely as possible to that of the diamond is required for this growth. Lattice mismatching should be reduced by employing a monocrystalline intermediate layer with lattice constants that lie between the lattice constants of the diamond and that of the substrate.